Services: Renamed from Servers

It didn't feel right to have a "DHCPClient" in a "Servers" directory.
Rename this to Services to better reflect the type of programs we'll
be putting in there.

1 files changed, 283 insertions, 0 deletions

diff --git a/Services/DHCPClient/DHCPv4Client.cpp b/Services/DHCPClient/DHCPv4Client.cpp
new file mode 100644
index 0000000000..918a20b93f
--- /dev/null
+++ b/Services/DHCPClient/DHCPv4Client.cpp
@@ -0,0 +1,283 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "DHCPv4Client.h"
+#include <AK/ByteBuffer.h>
+#include <AK/Function.h>
+#include <LibCore/SocketAddress.h>
+#include <LibCore/Timer.h>
+#include <stdio.h>
+
+//#define DHCPV4CLIENT_DEBUG
+
+static void send(const InterfaceDescriptor& iface, const DHCPv4Packet& packet, Core::Object*)
+{
+    int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+    if (fd < 0) {
+        dbg() << "ERROR: socket :: " << strerror(errno);
+        return;
+    }
+
+    if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, iface.m_ifname.characters(), IFNAMSIZ) < 0) {
+        dbg() << "ERROR: setsockopt(SO_BINDTODEVICE) :: " << strerror(errno);
+        return;
+    }
+
+    sockaddr_in dst;
+    memset(&dst, 0, sizeof(dst));
+    dst.sin_family = AF_INET;
+    dst.sin_port = htons(67);
+    dst.sin_addr.s_addr = IPv4Address { 255, 255, 255, 255 }.to_u32();
+    memset(&dst.sin_zero, 0, sizeof(dst.sin_zero));
+
+    auto rc = sendto(fd, &packet, sizeof(packet), 0, (sockaddr*)&dst, sizeof(dst));
+    if (rc < 0) {
+        dbg() << "sendto failed with " << strerror(errno);
+        // FIXME: what do we do here?
+    }
+}
+
+static void set_params(const InterfaceDescriptor& iface, const IPv4Address& ipv4_addr, const IPv4Address& netmask, const IPv4Address& gateway)
+{
+    int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
+    if (fd < 0) {
+        dbg() << "ERROR: socket :: " << strerror(errno);
+        return;
+    }
+
+    struct ifreq ifr;
+    memset(&ifr, 0, sizeof(ifr));
+    strncpy(ifr.ifr_name, iface.m_ifname.characters(), IFNAMSIZ);
+
+    // set the IP address
+    ifr.ifr_addr.sa_family = AF_INET;
+    ((sockaddr_in&)ifr.ifr_addr).sin_addr.s_addr = ipv4_addr.to_in_addr_t();
+
+    if (ioctl(fd, SIOCSIFADDR, &ifr) < 0) {
+        dbg() << "ERROR: ioctl(SIOCSIFADDR) :: " << strerror(errno);
+    }
+
+    // set the network mask
+    ((sockaddr_in&)ifr.ifr_netmask).sin_addr.s_addr = netmask.to_in_addr_t();
+
+    if (ioctl(fd, SIOCSIFNETMASK, &ifr) < 0) {
+        dbg() << "ERROR: ioctl(SIOCSIFNETMASK) :: " << strerror(errno);
+    }
+
+    // set the default gateway
+    struct rtentry rt;
+    memset(&rt, 0, sizeof(rt));
+
+    rt.rt_dev = const_cast<char*>(iface.m_ifname.characters());
+    rt.rt_gateway.sa_family = AF_INET;
+    ((sockaddr_in&)rt.rt_gateway).sin_addr.s_addr = gateway.to_in_addr_t();
+    rt.rt_flags = RTF_UP | RTF_GATEWAY;
+
+    if (ioctl(fd, SIOCADDRT, &rt) < 0) {
+        dbg() << "Error: ioctl(SIOCADDRT) :: " << strerror(errno);
+    }
+}
+
+DHCPv4Client::DHCPv4Client(Vector<InterfaceDescriptor> ifnames)
+    : m_ifnames(ifnames)
+{
+    m_server = Core::UDPServer::construct(this);
+    m_server->on_ready_to_receive = [this] {
+        auto buffer = m_server->receive(sizeof(DHCPv4Packet));
+        dbg() << "Received " << buffer.size() << " bytes";
+        if (buffer.size() != sizeof(DHCPv4Packet)) {
+            dbg() << "we expected " << sizeof(DHCPv4Packet) << " bytes, this is a bad packet";
+            return;
+        }
+        auto& packet = *(DHCPv4Packet*)buffer.data();
+        process_incoming(packet);
+    };
+
+    if (!m_server->bind({}, 68)) {
+        dbg() << "The server we just created somehow came already bound, refusing to continue";
+        ASSERT_NOT_REACHED();
+    }
+
+    for (auto& iface : m_ifnames)
+        dhcp_discover(iface);
+}
+
+DHCPv4Client::~DHCPv4Client()
+{
+}
+
+void DHCPv4Client::handle_offer(const DHCPv4Packet& packet, const ParsedDHCPv4Options& options)
+{
+    dbg() << "We were offered " << packet.yiaddr().to_string() << " for " << options.get<u32>(DHCPOption::IPAddressLeaseTime).value_or(0);
+    auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
+    if (!transaction) {
+        dbg() << "we're not looking for " << packet.xid();
+        return;
+    }
+    if (transaction->has_ip)
+        return;
+    if (transaction->accepted_offer) {
+        // we've accepted someone's offer, but they haven't given us an ack
+        // TODO: maybe record this offer?
+        return;
+    }
+    // TAKE IT...
+    transaction->offered_lease_time = options.get<u32>(DHCPOption::IPAddressLeaseTime).value();
+    dhcp_request(*transaction, packet);
+}
+
+void DHCPv4Client::handle_ack(const DHCPv4Packet& packet, const ParsedDHCPv4Options& options)
+{
+#ifdef DHCPV4CLIENT_DEBUG
+    dbg() << "The DHCP server handed us " << packet.yiaddr().to_string();
+    dbg() << "Here are the options: " << options.to_string();
+#endif
+    auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
+    if (!transaction) {
+        dbg() << "we're not looking for " << packet.xid();
+        return;
+    }
+    transaction->has_ip = true;
+    auto& interface = transaction->interface;
+    auto new_ip = packet.yiaddr();
+    auto lease_time = convert_between_host_and_network(options.get<u32>(DHCPOption::IPAddressLeaseTime).value_or(transaction->offered_lease_time));
+    // set a timer for the duration of the lease, we shall renew if needed
+    Core::Timer::create_single_shot(
+        lease_time * 1000,
+        [this, transaction, interface = InterfaceDescriptor { interface }, new_ip] {
+            transaction->accepted_offer = false;
+            transaction->has_ip = false;
+            dhcp_discover(interface, new_ip);
+        },
+        this);
+    set_params(transaction->interface, new_ip, options.get<IPv4Address>(DHCPOption::SubnetMask).value(), options.get_many<IPv4Address>(DHCPOption::Router, 1).first());
+}
+
+void DHCPv4Client::handle_nak(const DHCPv4Packet& packet, const ParsedDHCPv4Options& options)
+{
+    dbg() << "The DHCP server told us to go chase our own tail about " << packet.yiaddr().to_string();
+    dbg() << "Here are the options: " << options.to_string();
+    // make another request a bit later :shrug:
+    auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
+    if (!transaction) {
+        dbg() << "we're not looking for " << packet.xid();
+        return;
+    }
+    transaction->accepted_offer = false;
+    transaction->has_ip = false;
+    auto& iface = transaction->interface;
+    Core::Timer::create_single_shot(
+        10000,
+        [this, iface = InterfaceDescriptor { iface }] {
+            dhcp_discover(iface);
+        },
+        this);
+}
+
+void DHCPv4Client::process_incoming(const DHCPv4Packet& packet)
+{
+    auto options = packet.parse_options();
+#ifdef DHCPV4CLIENT_DEBUG
+    dbg() << "Here are the options: " << options.to_string();
+#endif
+    auto value = options.get<DHCPMessageType>(DHCPOption::DHCPMessageType).value();
+    switch (value) {
+    case DHCPMessageType::DHCPOffer:
+        handle_offer(packet, options);
+        break;
+    case DHCPMessageType::DHCPAck:
+        handle_ack(packet, options);
+        break;
+    case DHCPMessageType::DHCPNak:
+        handle_nak(packet, options);
+        break;
+    case DHCPMessageType::DHCPDiscover:
+    case DHCPMessageType::DHCPRequest:
+    case DHCPMessageType::DHCPRelease:
+        // These are not for us
+        // we're just getting them because there are other people on our subnet
+        // broadcasting stuff
+        break;
+    case DHCPMessageType::DHCPDecline:
+    default:
+        dbg() << "I dunno what to do with this " << (u8)value;
+        ASSERT_NOT_REACHED();
+        break;
+    }
+}
+
+void DHCPv4Client::dhcp_discover(const InterfaceDescriptor& iface, IPv4Address previous)
+{
+    auto transaction_id = rand();
+#ifdef DHCPV4CLIENT_DEBUG
+    dbg() << "Trying to lease an IP for " << iface.m_ifname << " with ID " << transaction_id;
+    if (!previous.is_zero())
+        dbg() << "going to request the server to hand us " << previous.to_string();
+#endif
+    DHCPv4PacketBuilder builder;
+
+    DHCPv4Packet& packet = builder.peek();
+    packet.set_op(DHCPv4Op::BootRequest);
+    packet.set_htype(1); // 10mb ethernet
+    packet.set_hlen(sizeof(MACAddress));
+    packet.set_xid(transaction_id);
+    packet.set_flags(DHCPv4Flags::Broadcast);
+    packet.ciaddr() = previous;
+    packet.set_chaddr(iface.m_mac_address);
+    packet.set_secs(65535); // we lie
+
+    // set packet options
+    builder.set_message_type(DHCPMessageType::DHCPDiscover);
+    auto& dhcp_packet = builder.build();
+
+    // broadcast the discover request
+    send(iface, dhcp_packet, this);
+    m_ongoing_transactions.set(transaction_id, make<DHCPv4Transaction>(iface));
+}
+
+void DHCPv4Client::dhcp_request(DHCPv4Transaction& transaction, const DHCPv4Packet& offer)
+{
+    auto& iface = transaction.interface;
+    dbg() << "Leasing the IP " << offer.yiaddr().to_string() << " for adapter " << iface.m_ifname;
+    DHCPv4PacketBuilder builder;
+
+    DHCPv4Packet& packet = builder.peek();
+    packet.set_op(DHCPv4Op::BootRequest);
+    packet.set_htype(1); // 10mb ethernet
+    packet.set_hlen(sizeof(MACAddress));
+    packet.set_xid(offer.xid());
+    packet.set_flags(DHCPv4Flags::Broadcast);
+    packet.set_chaddr(iface.m_mac_address);
+    packet.set_secs(65535); // we lie
+
+    // set packet options
+    builder.set_message_type(DHCPMessageType::DHCPRequest);
+    auto& dhcp_packet = builder.build();
+
+    // broadcast the "request" request
+    send(iface, dhcp_packet, this);
+    transaction.accepted_offer = true;
+}